The present invention relates to absorbent articles, and more particularly to disposable absorbent articles.
An assortment of absorbent articles of the disposable type have been proposed for use in receiving and retaining body fluids, such as disposable diapers and santiary pads. The articles may have a fluid impervious backing sheet, a fluid pervious top or cover sheet, and an absorbent pad between the backing and top sheets to capture the body fluids which pass through the top sheet. The pads are commonly made from a fibrous cellulosic material which provides the desired absorbent characteristics to the pad.
Although such pads may perform their absorbent function adequately upon receipt of the first or initial surge or surges of fluid, such as urine, it has been found that absorbency in the pads during subsequent use of the articles may be impaired due to the nature of the materials in the pad while in a wet condition. In particular, when the wet cellulosic fibers are placed under loads the fibers are compacted, thus reducing the interfiber spaces between fibers in the wet pad and compromising the absorptive capacity of the pad. For example, when a disposable diaper is wet by an infant, the weight placed by the infant on the wet diaper pad may sufficiently compact fibers in the pad such that the total absorptive capacity of the pad is reduced.
Of course, a solution of the absorbency problem would be satisfactory if the over-all cost of the disposable article is not significantly increased, and would be particularly desirable if, in fact, the cost of the article to the consumer is decreased. As will be seen below, a solution of a problem related to the manufacture of such articles also resolves the difficulty associated with absorbency of the articles during use.
The materials normally utilized in making the absorbent articles, e.g. disposable diapers, are described as follows. The fluid impervious backing sheets are made of a thermoplastic material, such as polyethylene, the fluid pervious top sheets are commonly made of a fibrous nonwoven material having a hydrophobic binder, while the absorbent pads are made of an absorbent cellulosic material, such as wood fluff. The diapers are usually provided with tape fasteners for securing the diapers about infants. Such fasteners have a backing commonly made of a thermoplastic or paper material and an adhesive coating on one surface of the fastener backing. It will be seen that the basic components of the diaper are products of natural resources and are costly, viz., trees and oil, and are likely to be so in the future. Hydrocarbon feed stuffs from oil are utilized to make the backing sheets, and possibly the adhesive and backings of the tape fasteners, while fibers formed from appropriate wood pulp are utilized to make the absorbent pads, the top sheets, and possibly the fastener backings of the diapers.
Yet the manufacture of such articles, which have come into every day use, is attendant with waste resulting in disposal of large quantities of such valuable materials. For example, when manufacture of such articles is initiated on a machine, a substantial amount of the materials may be utilized before a satisfactory article is obtained for packaging and sale, and the initial portion of such materials produced during the setup procedure would normally be discarded as waste. Additional waste materials may be accumulated while the machine is not functioning properly, during unscheduled stops of the machine, after breakage of materials utilized in making the articles, or during changes of raw material sources supplied to the machine.
In each case, the rejected materials have been discarded or destroyed in the past as waste, resulting in loss of valuable natural resources. For example, the waste materials may be utilized for purposes of packing, resulting in minimal use of the materials relative to their value. Alternatively, the materials may be burned or used as land fill, where permitted, which is wasteful and generally undesirable from an ecological point of view.